An existing VG 70-70F instrument will be upgraded under funds provided by the Division of Research Resources - Biomedical Research Support Shared Instrumentation Grants Program. The upgrade will include turn-key data system, extended geometry configuration with laminated magnet, fast atom bombardment and field desorption capabilities. The modified instrument will serve the research programs of the above listed major investigators and many other members of the biomedical research community in providing the means for the structural analysis of many important classes of molecules of biomedical interest, including polar and/or thermally labile compounds, which cannot be analysed using the currently available instrument. The addition of the data system is a particularly critical need which will provide many new capabilities and efficiency of operation in a multi-user format.